1. Technical Field
The present disclosure relates to a propeller shaft to be used in a vehicle and the like, and particularly relates to a divided propeller shaft.
2. Description of Related Art
For example, a so-called FR vehicle with a front engine and a rear-wheel drive uses a propeller shaft in order to transmit a driving force from the engine to rear wheels. The propeller shaft is required to have high durability, and the propeller shaft is firm. Further, a divided propeller shaft including a plurality of shaft members arranged in a vehicle front-rear direction so as to be connected to each other is used conventionally.
In the meantime, at the time of a vehicle collision, an engine room is destroyed effectively with respect to an impact from a front side, so as to relax the impact, thereby making it possible to protect an occupant. At this time, it is proposed that the engine inside the engine room is configured to move rearward toward a vehicle rear side and the propeller shaft is configured to be contractible axially so that the propeller shaft also absorbs the impact. One example of such an impact absorption structure of the propeller shaft is described in Japanese Patent Application Publication No. 2006-123781 (JP 2006-123781 A).
JP 2006-123781 A describes a propeller shaft configured such that a first shaft on a front side of a vehicle is connected to a second shaft on a rear side by a tripod-type constant velocity joint, an outer member of the constant velocity joint is provided in a rear end of the first shaft, and a center bearing is provided slidably in a connecting shaft portion of the second shaft configured such that its inner-member attached distal end is inserted into in the outer member. At the time of a vehicle collision, the first shaft on the front side moves rearward relative to the second shaft on the rear side due to an impact force from a vehicle front side, and the outer member of the first shaft collides with the center bearing provided in the second shaft. The center bearing is press-fitted to an outer peripheral surface of an intermediate shaft portion of the connecting shaft portion having a uniform diameter so that the center bearing slides on the connecting shaft portion of the second shaft toward a rear side of the vehicle due to a force from the outer member. The sliding of the center bearing causes a sliding frictional force between an inner peripheral surface of the center bearing and the outer peripheral surface of the intermediate shaft portion of the second shaft. Due to the frictional force, an impulse force to the vehicle is absorbed.